Communication system

ABSTRACT

A communication system is described in which system information is transmitted to communication devices, by a communication apparatus of the system, in system information blocks, in accordance with a system information block transmission scheme. The communication apparatus configures at least one system information block to include control information indicating how the system information blocks will be transmitted.

TECHNICAL FIELD

The present invention relates to mobile communications devices andnetworks, particularly but not exclusively those operating according tothe 3^(rd) Generation Partnership Project (3GPP) standards orequivalents or derivatives thereof. The invention has particularalthough not exclusive relevance to the Long Term Evolution (LTE) ofUTRAN (called Evolved Universal Terrestrial Radio Access Network(E-UTRAN)), including LTE-Advanced.

BACKGROUND ART

In a mobile (cellular) communications network, (user) communicationdevices (also known as user equipment (UE), for example mobiletelephones) communicate with remote servers or with other communicationdevices via base stations. In their communication with each other,communication devices and base stations use licensed radio frequencies,which are typically divided into frequency bands and/or time blocks.

In order to be able to communicate via the base stations, communicationdevices need to monitor control channels operated by the base stations.One of these physical control channels, the so-called physical downlinkcontrol channel (PDCCH) carries control information for scheduling ofdownlink and uplink resources to individual communication devices.Physical downlink control (PDCCH) channels are transmitted on anaggregation of one or several consecutive control channel elements(CCEs). Scheduling is realised by the serving base station transmitting,over the PDCCH, a Downlink Control Information (DCI) to eachcommunication device that has been scheduled resources in the currentscheduling round. Downlink data that has been scheduled this way istransmitted over the so-called Physical Downlink Shared Channel (PDSCH)using the resources allocated by the DCI. The PDSCH resources associatedwith the PDCCH control information (DCI) are normally provided withinthe same subframe, albeit using different frequencies.

Common control transmissions include, for example: Master InformationBlock (MIB) and System Information Block (SIB) broadcast; Random AccessResponse (RAR) messages; and Paging.

In order to communicate with the network the UE must obtain systeminformation. System information includes configuration information aboutthe network and the serving cell. Since this information is common toall users of the cell, it is broadcast to all UEs in the cell coveragearea. System information is grouped into messages called the MasterInformation Block (MIB) and a number of System Information Blocks(SIBs). The MIB includes the most essential system information needed bythe UE to acquire other information from the cell: the system bandwidth,the System Frame Number (SFN), and the Physical Hybrid Automatic RepeatRequest (HARQ) Indicator Channel (PHICH) Configuration. The MIB iscarried on the Broadcast Channel (BCH) mapped into the PhysicalBroadcast Channel (PBCH). This is transmitted with a fixed coding andmodulation scheme and can be decoded after the initial cell searchprocedure. The MIB uses a fixed schedule with a periodicity of 40 ms andrepetitions made within 40 ms. With the information obtained from theMIB the UE can then decode the Control Format Indicator (CFI), whichindicates the PDCCH length. This allows the PDCCH to be decoded. Thepresence in the PDCCH of a DCI message scrambled with System InformationRadio Network Temporary Identifier (SI-RNTI) indicates that a SIB iscarried in the same subframe.

The SIBs are transmitted in the Broadcast Control Channel (BCCH) logicalchannel. Generally, BCCH messages are carried on the Downlink SharedChannel (DL-SCH) and transmitted on the PDSCH at periodic intervals. Theformat and resource allocation of the PDSCH transmission is indicated bya DCI message on the PDCCH. LTE/LTE-A defines different SIBs accordingto the type of system information that each SIB conveys. For example,SIB1 includes cell access information, including cell identityinformation, and it may indicate whether a UE is allowed to camp on aneNB. SIB1 also includes cell selection information (or cell selectionparameters). Additionally, SIB1 includes scheduling information forother SIBs. Not all SIBs need to be present. Similar to MIBs, the SIBsare broadcast repeatedly. In general, a lower-order SIB is more timecritical and is transmitted more often compared to a higher-order SIB.SIB1 is transmitted every 80 ms, whereas the transmission period for thehigher-order SIBs is flexible and can be different for differentnetworks. SIBs other than SIB1 are carried in System Information (SI)messages. Mapping of SIBs to SI messages is configured flexibly byscheduling information included in SIB Type 1 with some restrictions,including that only SIBs with the same scheduling requirement(periodicity) can be mapped to the same SI message.

After the system information of a cell has been acquired, the UE canattempt to establish an initial connection by sending a short message onthe random access channel. To minimize the possibility that severaldevices attempt to send a message simultaneously which results in anetwork access collision, firstly the message itself is only very shortand only contains a 5 bit random number. Furthermore, the network offersmany random access slots per second to randomize access requests overtime. When the network picks up the random access request, it assigns aCell-Radio Network Temporary Identifier (C-RNTI) to the mobile andanswers the message with a Random Access Response message. In addition,the message contains an initial uplink bandwidth grant, that is, a setof resource blocks of the shared uplink channel that the UE can use inthe uplink direction. These resources are then used to send the RRCconnection request message that encapsulates an initial attach request.

The main purpose of a paging message is to page UEs in RRC_IDLE mode fora mobile terminated call. Also the paging message can be used to informUEs, in RRC_IDLE as well as RRC_CONNECTED modes, that system informationwill be changed or that the ETWS notification is posted in SIB10 or SIB11.

Recent developments in telecommunications have seen a large increase inthe use of machine-type communications (MTC) UEs which are networkeddevices arranged to communicate and perform actions without humanassistance. Examples of such devices include smart meters, which can beconfigured to perform measurements and relay these measurements to otherdevices via a telecommunication network. Machine-type communicationdevices are also known as machine-to-machine (M2M) communicationdevices.

MTC devices connect to the network whenever they have data to send to orreceive from a remote ‘machine’ (e.g. a server) or user. MTC devices usecommunication protocols and standards that are optimised for mobiletelephones or similar user equipment. However, MTC devices, oncedeployed, typically operate without requiring human supervision orinteraction, and follow software instructions stored in an internalmemory. MTC devices might also remain stationary and/or inactive for along period of time. The specific network requirements to support MTCdevices have been dealt with in the 3GPP TS 22.368 standard, thecontents of which are incorporated herein by reference.

For the Release 13 (Rel-13) version of the standards relating to MTCdevices, support for a reduced bandwidth of 1.4 MHz in downlink anduplink is envisaged. Thus, some MTC devices (referred to as ‘reducedbandwidth MTC devices’) will support only a limited bandwidth (typically1.4 MHz) compared to the total LTE bandwidth and/or they may havefewer/simplified components. This allows such ‘reduced bandwidth’ MTCdevices to be made more economically compared to MTC devices supportinga larger bandwidth and/or having more complicated components.

Further, the lack of network coverage (e.g. when deployed indoors), incombination with the often limited functionality of MTC devices, canresult in such MTC devices having a low data rate and therefore there isa risk of some messages or channels not being received by an MTC device.In order to mitigate this risk, it has been proposed to increase thecoverage of the PDCCH (or enhanced PDCCH (‘EPDCCH’) in Rel-13) tosupport such MTC devices (e.g. corresponding to 20 dB for frequencydivision duplex (FDD) transmissions). To facilitate such enhancedcoverage, each MTC device will need to inform its serving base stationof the amount of coverage required (e.g. 5 dB/10 dB/15 dB/20 dB coverageenhancement) to allow the base station to adjust its control signallingappropriately.

Ideally, physical layer control signalling (such as (E)PDCCH, PUCCH,and/or the like) and higher layer common control information (e.g. SIB,random access response (RAR), paging messages, and/or the like) exhibita high level of commonality between solutions for reduced bandwidthcommunication devices and solutions for coverage enhanced communicationdevices.

3GPP has recently agreed on LTE Physical Layer Enhancements for MTC inRel-13, including agreements on PBCH and unicast transmission. For PBCH,it will use the legacy mechanism with more repetition. For unicasttransmission: PDSCH transmission will be scheduled by ‘physical downlinkcontrol channel for MTC’ with cross-subframe scheduling supported.However, it is not yet known how to schedule certain common controltransmissions (e.g. SIB/RAR/Paging common control messages) for MTCdevices. There are at least two options, which are described below.

SUMMARY OF INVENTION Technical Problem

The first option involves control-less common control transmission. Thisis a PBCH-like design in which transmission timing, resource allocation(RA) and transmission formats (MCS, RV, etc.) are predefined for thecommon control information transmission. Furthermore, the TransportBlock Size (TBS)/message size is fixed. For example, infrequency-domain, all 6 RBs in 1.4 MHz are used to carry SIB, and also apredefined periodicity in time-domain. An advantage of this option isthat it provides overhead reduction as well as power consumptionreduction at the UE, due to elimination of the control transmission.However, a disadvantage of this is that it lacks eNodeB schedulingflexibility.

The second option involves EPDCCH Common Search Space (CSS)transmission, which defines CSS in EPDCCH to provide dynamic schedulingfor the common control information for Rel-13 low complexity UEs. Anadvantage of this option is the eNodeB scheduling flexibility thatachieves an efficient system operation. However, a disadvantage of thisis the control overhead increase compared to the first option, morespecifically for coverage enhanced mode where a significant number ofrepetitions of the SIBs are needed.

The present invention seeks to provide systems, devices and methodswhich at least partially address the above issues.

Solution to Problem

In one aspect, the invention provides a communication apparatus for acommunication system in which system information is transmitted tocommunication devices, by the communication apparatus, in systeminformation blocks transmitted in accordance with a system informationblock transmission scheme, the communication apparatus comprising: meansfor operating a cell; means for configuring at least one systeminformation block to include control information for indicating at leastone of the following: (i) which of a plurality of different systeminformation block transmission schemes the system information blockswill be transmitted in accordance with, wherein each of said pluralityof different system information block transmission schemes involves thetransmission of system information blocks of a different respectivesize; (ii) whether or not said at least one system information block hasbeen extended; and (iii) whether or not at least one further systeminformation block will be transmitted after said at least one systeminformation block; and means for transmitting, to the communicationdevices within the cell, said system information blocks in accordancewith said system information block transmission scheme.

In one aspect, the invention provides a communication apparatus for acommunication system in which system information is transmitted tocommunication devices, by the communication apparatus, in systeminformation blocks transmitted in accordance with a system informationblock transmission scheme, the communication apparatus comprising: meansfor operating a cell; means for transmitting, to the communicationdevices within the cell, said system information blocks in accordancewith any of a plurality of system information block transmissionschemes, wherein each system information transmission scheme involvesthe transmission of system information blocks of a different respectivesize.

In one aspect, the invention provides a communication device for acommunication system in which system information is transmitted bycommunication apparatus, to the communication device, in systeminformation blocks transmitted in accordance with a system informationblock transmission scheme, the communication device comprising: meansfor communicating with the communication apparatus within a celloperated by that communication apparatus, wherein the means forcommunicating is operable to receive, from the communication apparatus,at least one system information block configured to include controlinformation for indicating at least one of the following: (i) which of aplurality of different system information block transmission schemes thesystem information block will be transmitted in accordance with, whereineach of said plurality of different system information blocktransmission schemes involves the transmission of system informationblocks of a different respective size; (ii) whether or not said at leastone system information block has been extended; and (iii) whether or notat least one further system information block will be transmitted aftersaid at least one system information block; and means for obtaining thesystem information from one or more system information blocks based onwith the control information.

In one aspect, the invention provides a communication device for acommunication system in which system information is transmitted bycommunication apparatus, to the communication device, in systeminformation blocks transmitted in accordance with a system informationblock transmission scheme, the communication device comprising: meansfor communicating with the communication apparatus within a celloperated by that communication apparatus, wherein the means forcommunicating is operable to receive, from the communication apparatus,said system information blocks in accordance with any of a plurality ofsystem information block transmission schemes, wherein each systeminformation block transmission scheme involves the transmission ofsystem information blocks of a different respective size; and means forobtaining the system information from one or more system informationblocks by attempting to decode the one or more system information blocksin accordance with a first of said system information transmissionschemes and, if unsuccessful, attempting to decode the one or moresystem information blocks in accordance with another of said systeminformation block transmission schemes.

In one aspect, the invention provides a method performed by acommunication apparatus for a communication system in which systeminformation is transmitted to communication devices, by thecommunication apparatus, in system information blocks transmitted inaccordance with a system information block transmission scheme, themethod comprising: operating a cell; configuring at least one systeminformation block to include control information for indicating at leastone of the following: (i) which of a plurality of different systeminformation block transmission schemes the system information blockswill be transmitted in accordance with, wherein each of said pluralityof different system information block transmission schemes involves thetransmission of system information blocks of a different respectivesize; (ii) whether or not said at least one system information block hasbeen extended; and (iii) whether or not at least one further systeminformation block will be transmitted after said at least one systeminformation block; and transmitting, to communication devices within thecell, said system information blocks in accordance with said systeminformation block transmission scheme.

In one aspect, the invention provides a method performed by acommunication apparatus for a communication system in which systeminformation is transmitted to communication devices, by thecommunication apparatus, in system information blocks transmitted inaccordance with a system information block transmission scheme, themethod comprising: operating a cell; transmitting, to the communicationdevices within the cell, said system information blocks in accordancewith any of a plurality of system information block transmissionschemes, wherein each system block information transmission schemeinvolves the transmission of system information blocks of a differentrespective size.

In one aspect, the invention provides a method performed by acommunication device for a communication system in which systeminformation is transmitted by communication apparatus, to thecommunication device, in system information blocks transmitted inaccordance with a system information block transmission scheme, thecommunication device comprising: communicating with the communicationapparatus within a cell operated by that communication apparatus,wherein the means for communicating is operable to receive, from thecommunication apparatus, at least one system information blockconfigured to include control information for indicating at least one ofthe following: (i) which of a plurality of different system informationblock transmission schemes the system information blocks will betransmitted in accordance with, wherein each of said plurality ofdifferent system information block transmission schemes involves thetransmission of system information blocks of a different respectivesize; (ii) whether or not said at least one system information block hasbeen extended; and (iii) whether or not at least one further systeminformation block will be transmitted after said at least one systeminformation block; and obtaining the system information from one or moresystem information blocks based on the control information.

In one aspect, the invention provides a method performed by acommunication device of a communication system in which systeminformation is transmitted by communication apparatus, to thecommunication device, in system information blocks transmitted inaccordance with a system information block transmission scheme, themethod comprising: communicating with the communication apparatus withina cell operated by that communication apparatus, wherein the means forcommunicating is operable to receive, from the communication apparatus,said system information blocks in accordance with any of a plurality ofsystem information block transmission schemes, wherein each systeminformation block transmission scheme involves the transmission ofsystem information blocks of a different respective size; and obtainingthe system information from one or more system information blocks byattempting to decode the one or more system information blocks inaccordance with a first of said system information transmission schemesand, if unsuccessful, attempting to decode the one or more systeminformation blocks in accordance with another of said system informationblock transmission schemes.

Aspects of the invention extend to corresponding systems, methods, andcomputer program products such as computer readable storage media havinginstructions stored thereon which are operable to program a programmableprocessor to carry out a method as described in the aspects andpossibilities set out above or recited in the claims and/or to program asuitably adapted computer to provide the apparatus recited in any of theclaims.

Each feature disclosed in this specification (which term includes theclaims) and/or shown in the drawings may be incorporated in theinvention independently (or in combination with) any other disclosedand/or illustrated features. In particular but without limitation thefeatures of any of the claims dependent from a particular independentclaim may be introduced into that independent claim in any combinationor individually.

Exemplary embodiments of the invention will now be described by way ofexample only with reference to the attached figures in which:

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 schematically illustrates a telecommunication system to whichembodiments of the invention may be applied;

FIG. 2 is a block diagram illustrating the main components of thecommunication device shown in FIG. 1;

FIG. 3 is a block diagram illustrating the main components of the basestation shown in FIG. 1;

FIG. 4 illustrates an exemplary way in which an MTC specific commoncontrol signalling can be provided in the system shown in FIG. 1;

FIG. 5 illustrates an exemplary way in which an MTC specific commoncontrol signalling can be provided in the system shown in FIG. 1;

FIG. 6 illustrates an exemplary way in which an MTC specific commoncontrol signalling can be provided in the system shown in FIG. 1;

FIG. 7 illustrates an exemplary way in which an MTC specific commoncontrol signalling can be provided in the system shown in FIG. 1;

FIG. 8 illustrates an exemplary way in which an MTC specific commoncontrol signalling can be provided in the system shown in FIG. 1;

FIG. 9 illustrates an exemplary way in which an MTC specific commoncontrol signalling can be provided in the system shown in FIG. 1;

FIG. 10a illustrates an exemplary way in which an MTC specific commoncontrol signalling can be provided in the system shown in FIG. 1;

FIG. 10b illustrates an exemplary way in which an MTC specific commoncontrol signalling can be provided in the system shown in FIG. 1;

FIG. 11a illustrates an exemplary way in which an MTC specific commoncontrol signalling can be provided in the system shown in FIG. 1; and

FIG. 11b illustrates an exemplary way in which an MTC specific commoncontrol signalling can be provided in the system shown in FIG. 1.

DESCRIPTION OF EMBODIMENTS Overview

FIG. 1 schematically illustrates a mobile (cellular) telecommunicationsystem 1 in which user equipment 3 (communication devices such as mobiletelephone 3-1 and MTC device 3-2) can communicate with each other and/orwith other communication nodes via an E-UTRAN base station 5 (denoted‘eNB’) and a core network 7. As those skilled in the art willappreciate, whilst one mobile telephone 3-1, one MTC device 3-2, and onebase station 5 are shown in FIG. 1 for illustration purposes, thesystem, when implemented, will typically include other base stations andcommunication devices.

The base station 5 is connected to the core network 7 via an S1interface. The core network 7 includes, amongst others: a gateway forconnecting to other networks, such as the Internet and/or to servershosted outside the core network 7; a mobility management entity (MME)for keeping track of the locations of the communication devices 3 (e.g.the mobile telephone and the MTC device) within the communicationnetwork 1; and a home subscriber server (HSS) for storing subscriptionrelated information (e.g. information identifying which communicationdevice 3 is configured as a machine-type communication device) and forstoring control parameters specific for each communication device 3.

The base station 5 is configured to provide a number of controlchannels, including, for example, a physical downlink control channel(PDCCH) and a physical uplink control channel (PUCCH). The PDCCH is usedby the base station 5 for allocating resources to the communicationdevices 3 (typically by sending a UE-specific DCI to each communicationdevice that has been scheduled in the current scheduling round). ThePUCCH is used by the communication devices 3 for sending a UE-specificUCI to the base station (e.g. an appropriate HARQ Ack/Nack correspondingto downlink data received using the resources allocated by the DCI).

Each communication device 3 may fall into one or more of categories ofUEs. A first category of UEs include communication devices that supportonly an earlier release of the LTE standard (e.g. Rel-8, Rel-9, Rel-10,Rel-11, and/or Rel-12). Such group of communication devices are commonlyreferred to as legacy UEs (assuming that the base station 5 is operatingin accordance with Rel-13 of the LTE standards). A second category ofUEs include reduced bandwidth UEs (e.g. Rel-13 MTC devices capable ofusing a 1.4 Mhz bandwidth only), which are not able to communicate overthe entire bandwidth available in the cell of the base station 5. Athird category of UEs includes coverage enhanced UEs (e.g. some MTCdevices), which require certain base station functionalities to besimplified and/or relaxed (although such coverage enhanced UEs maysupport other functionalities as normal).

Beneficially, in order to support (but not limited to use with) reducedbandwidth MTC devices, the telecommunication system employs an enhancedcontrol-less common control transmission scheme in which the amount ofsystem information transmitted and/or the number of repetitions of thesystem information, can be varied flexibly depending on requirementswithout a significant increase in signalling overhead to inform theUE(s).

Specifically, the enhanced control-less common control transmissionscheme has the potential to allow a relatively small or relatively largeamount of system information to be transmitted in an optimum manner andprovides the flexibility for the scheme to be extended further, withrelatively little impact, to allow even larger amounts of systeminformation to be transmitted in the future (e.g. for compatibility withfuture releases of the standards).

A number of specific embodiments of the enhanced control-less commoncontrol transmission scheme are now summarised by way of example.

In one exemplary embodiment, for example, the enhanced control-lesscommon control transmission scheme uses spare bits of a MIB to indicateone of a plurality of different predetermined TBS/message sizes and/orcorresponding scheduling scheme (number of repetitions). Advantageously,the number of spare bits required is minimized (e.g., two to represent apossible four different schemes). This is because transmissionparameters such as the modulation scheme or coding rate can be fixed orimplicitly depend on the TBS/message size and/or number of repetitions.

In an variation to the above exemplary embodiment, the UE is notexplicitly informed of which of the predetermined TBS and schedulingschemes is used but instead performs blind decoding to detect whichmessage transmission format is used. Beneficially, this minimises thechanges to current system elements required to implement the proposalsand in particular minimises the impact on signalling configurations andoverhead albeit at the expense of the resources required to perform theblind decoding.

In another exemplary embodiment, for example, the enhanced control-lesscommon control transmission scheme uses bit(s) in an MTC-SIB to indicatethat an extension to the MTC-SIB(s) is being provided. This has theadvantage of improved backward/forward compatibility. For example,Rel-13 MTC UEs only needs to read the Rel-13 part of SI regardless ofthe extension availability whereas a later release UE can read theextended part based on the availability bit and corresponding schedulinginformation, which in this example is pre-configured (e.g. in accordancewith a standards specification of the corresponding release) but couldbe provided dynamically in the MTC-SIB.

In yet another exemplary embodiment, for example, the enhancedcontrol-less common control transmission scheme uses bit(s) in anMTC-SIB to indicate that one or more further MTC-SIBs will betransmitted.

In yet another exemplary embodiment the enhanced control-less commoncontrol transmission scheme provides a dedicated ‘scheduling’ or‘Master’ MTC-SIB including information which indicates the existence ofany other MTC-SIBs which will be transmitted.

It will be appreciated that, in any of the aforementioned embodiments,one or more additional bits can be used to dynamically indicate(additional) scheduling information (e.g. information such asperiodicity, offset, repeating times/window, resource allocation(s),transmission format and/or the like) for the future SIB(s) (either inthe form of specific scheduling information or in the form of anidentity of one of a plurality of pre-configured schemes). However, theprovision of such (additional) scheduling information dynamically isentirely optional and the scheduling information can be preconfiguredinstead.

Therefore, in effect, the above exemplary embodiments provide anadvantageous solution which provides possible advantages over both thecontrol-less common control transmission option and the EPDCCH CommonSearch Space (CSS) transmission option referred to in the backgroundsection and also opens the possibility to extend the SIB size in thefuture as well as improving scheduling flexibility.

Communication Device

FIG. 2 is a block diagram illustrating the main components of thecommunication device 3 shown in FIG. 1. The communication device 3 maybe an MTC device or a mobile (or ‘cellular’) telephone configured as amachine-type communication device. The communication device 3 comprisesa transceiver circuit 31 which is operable to transmit signals to, andto receive signals from, the base station 5 via at least one antenna 33.Typically, the communication device 3 also includes a user interface 35which allows a user to interact with the communication device 3, howeverthis user interface 35 may be omitted for some MTC devices.

The operation of the transceiver circuit 31 is controlled by acontroller 37 in accordance with software stored in memory 39. Thesoftware includes, among other things, an operating system 41, acommunication control module 43, an MTC module 45, and a systeminformation module 47.

The communication control module 43 controls communications between thecommunication device 3 and the base station 5 and/or other communicationnodes (via the base station 5). As shown in FIG. 2, the communicationcontrol module 43 includes, amongst others, an EPDCCH module portion(for managing communications over the enhanced physical downlink controlchannel), a PDSCH module portion (for managing communications over thephysical downlink shared channel), and a PUCCH module portion (formanaging communications over the physical uplink control channel). TheMTC module 45 is operable to carry out machine-type communication tasks.For example, the MTC module 45 may (e.g. periodically) receive data froma remote server (via the transceiver circuit 31) over resourcesallocated to the MTC device 3 by the base station 5. The MTC module 45may also collect data for sending (e.g. periodically and/or upondetecting a trigger) to a remote server (via the transceiver circuit31).

The system information module 47 is responsible for locating,identifying and decoding system information received in systeminformation blocks via the antenna 33 and transceiver circuit 31, inaccordance with the enhanced control-less common control transmissionscheme of any of the embodiments described herein.

Base Station

FIG. 3 is a block diagram illustrating the main components of the basestation 5 shown in FIG. 1. The base station 5 comprises an E-UTRAN basestation (eNB) comprising a transceiver circuit 51 which is operable totransmit signals to, and to receive signals from, the communicationdevices 3 via one or more antennas 53. The base station 5 is alsooperable to transmit signals to and to receive signals from a corenetwork 7 via an appropriate core network interface 55 (such as an S1interface). The operation of the transceiver circuit 51 is controlled bya controller 57 in accordance with software stored in memory 59.

The software includes, among other things, an operating system 61, acommunication control module 63, a UE category determination module 65and a system information module 67.

The communication control module 63 controls communications with thecommunication devices 3 (including any MTC devices). The communicationcontrol module 63 is also responsible for scheduling the resources to beused by the communication devices 3 served by this base station 5. Asshown in FIG. 3, the communication control module 63 includes, amongstothers, an EPDCCH module portion (for managing communications over theenhanced physical downlink control channel), a PDSCH module portion (formanaging communications over the physical downlink shared channel), anda PUCCH module portion (for managing communications over the physicaluplink control channel).

The UE category determination module 65 determines the category of thecommunication devices 3 served by the base station 5, based on, forexample, information obtained from the communication devices 3 and/orfrom another network node (e.g. the HSS). When appropriate, the UEcategory determination module 65 provides information identifying thecategory of each served communication devices to the other modules, e.g.the communication control module 53, so that the other modules canadjust their operation accordingly.

The system information module 67 is responsible for managing thetransmission of system information in system information blocks via theantenna 53 and the transceiver circuit 51, in accordance with theenhanced control-less common control transmission scheme of any of theexemplary embodiments described herein.

In the above description, the communication device 3 and the basestation 5 are described for ease of understanding as having a number ofdiscrete modules. Whilst these modules may be provided in this way forcertain applications, for example where an existing system has beenmodified to implement the invention, in other applications, for examplein systems designed with the inventive features in mind from the outset,these modules may be built into the overall operating system or code andso these modules may not be discernible as discrete entities.

The following is a description of various ways in which common controlsignalling may be provided in LTE systems.

System Information for Rel-13 Low Complexity UEs

As noted earlier, for the Rel-13 version of the standards relating toMTC devices a number of requirements compared to legacy systems havebeen decided. For example, the system information has to repeat enoughtimes to make sure 15 dB coverage improvement UEs can receive SIBscorrectly. However, more repetitions are needed for bigger TB sizes.Thus, it would be desirable to limit any increase in size while alsoproviding scheduling flexibility. On the other hand, this may limitpossible further extensions in future releases.

These issues may be overcome or ameliorated by employing one or more ofthe following enhanced control-less common control transmission examples1 to 4 described below. The concept is based on the idea of finding animproved control-less common control transmission which providespossible advantages over both the control-less common controltransmission option and the EPDCCH Common Search Space (CSS)transmission option and also opens the possibility of extending the SIBsize in the future as well as improving scheduling flexibility.

EXAMPLE 1 Operation—First Example

A first exemplary way in which an MTC common control transmission can beprovided in the system shown in FIG. 1 is illustrated in FIG. 4.

As seen in FIG. 4, at step S410, a MIB is sent by the base station 5 tothe UE 3 and number of bits in the MIB are used to indicate one of aplurality of predefined system information transmission schemes eachrepresenting a different respective configuration of transmission blocksize (TBSs), corresponding scheduling scheme, and number of repetitions.In particular, four combinations of two bits are defined as follows:

-   -   “00” indicates a TBS of 152 bits, time domain repetition N1;    -   “01” indicates a TBS of 256 bits, time domain repetition N2        (N2>N1);    -   “10” indicates a TBS of 328 bits, time domain repetition N3        (N3>N2); and    -   “11” indicates a TBS of 504 bits, time domain repetition N4        (N4>N3).

The predefined values N1, N2, N3 and N4 are the number of repetitionsneeded to achieve the same coverage target for the respective TBSs.

Thus, in this example the TBS/message size is variable and signalled inthe MIB. Likewise, the repetitions in time-domain are variable anddepend on the TBS size to reach the enhanced coverage target. On theother hand, the resource allocation (RA) is fixed to 6 Resource Blocks(RBs) in the frequency domain and the modulation is fixed to QPSK.Furthermore, the coding rate implicitly depends on the TBS size. Assuch, it is not necessary to transmit information indicating theresource allocation, the modulation or the coding rate.

At step S411, the UE 3 identifies from the corresponding bits of the MIBwhich of the plurality of predefined system information transmissionschemes will be used for SIB transmission and hence what predefinedtransmission block size (TBSs), corresponding scheduling scheme andnumber of repetitions will be used.

At step S412-0, the first SIB is sent by the base station 5 inaccordance with the system information transmission scheme it identifiedin the MIB. This procedure is then repeated (if required) in accordancewith the system information transmission scheme identified in the MIB asillustrated by steps S412-1, S412-2 (two repetitions are shown forsimplicity but any number—including no repetitions—are possible). Then,after the number of repetitions for the identified scheme, at step S414,the UE 3 decodes the soft combination of the received SIBs based on thesystem information transmission scheme that it identified form the MIBin order to derive the system information. It will be appreciated thatwhilst, in this example, the decoding of the soft combination takesplace after a number of SIB transmission repetitions, the softcombination itself will take place cumulatively after every SIBretransmission.

Although in this particular example two bits in the MIB are used, itwill be understood that fewer or more bits could be used depending onthe number of predefined TBS sizes.

In a variant of this example, illustrated in FIG. 5, the communicationdevice 3 (e.g., MTC device 3-2) is not informed by the base station 5 ofthe system information transmission scheme being used and so does notautomatically know the TBS and number of repetitions but insteadperforms ‘blind decoding’ to determine which TBS is being used.

Specifically, in this variant the base station 5 simply sends the firstSIB in accordance with an unidentified system information transmissionscheme. This procedure is then repeated (e.g. steps S512-1, S512-2,S512-3, S512-4) for the number of repetitions associated with the systeminformation transmission scheme. At step S514-0, following the number ofrepetitions associated with the system information transmission schemeinvolving the smallest TBS (and hence the smallest number ofrepetitions) the UE 3 attempts to decode the previously received SIBsusing soft combination of all repetitions from the first repetition tothe latest repetition based on that system information transmissionscheme. If decoding is not successful, then at step S514-1, following atotal number of repetitions associated with the system informationtransmission scheme involving the next smallest TBS (and hence the nextsmallest number of repetitions) the UE 3 attempts to decode thepreviously received SIBs using soft combination of all repetitions fromthe first repetition to the latest repetition based on that systeminformation transmission scheme. This procedure continues untilsuccessful decoding is achieved. It will be appreciated that whilst, inthis example, the attempted decoding of the soft combination takes placeafter a number of SIB transmission repetitions, and then if unsuccessfulafter another number of SIB transmission repetitions, the softcombination itself will take place cumulatively after every SIBretransmission.

The procedure is explained in more detail below with reference to theaforementioned exemplary TBSs and corresponding scheduling schemes.

-   -   (i) For repetitions 1 to N1, the communication device 3 attempts        soft combination and decoding of the TB assuming a TBS of 152        bits;    -   (ii) If (i) fails, then during repetitions N+1 to N2, the        communication device 3 attempts decoding of the TB assuming a        TBS of 256 bits using soft combination of all repetitions from 1        up to the latest repetition (i.e. N2);    -   (iii) If (ii) fails, then during repetitions N+2 to N3, the        communication device 3 attempts decoding of the TB assuming a        TBS of 328 bits using soft combination of all repetitions from 1        up to the latest repetition (i.e. N3);    -   (iv) If (iii) fails, then for repetitions N+3 to N4, the        communication device 3 attempts decoding of the TB assuming a        TBS of 504 bits using soft combination of all repetitions from 1        up to the latest repetition (i.e. N4).

It will be appreciated that in either variant of this example the UE maydecode or attempt to decode the soft combination of previously receivedSIBs at any appropriate interval (e.g. after every repetition or afterevery other repetition, or the like).

EXAMPLE 2 Operation—Second Example

A second exemplary way in which an MTC common control transmission canbe provided in the system shown in FIG. 1 is illustrated in FIG. 6 inwhich bits of one or more dedicated MTC-SIB(s) are used to indicate thepresence of an extension to the MTC-SIB(s).

As seen in FIG. 6, each MTC-SIB, 402-1 to 402-n, can include one (ormore) bit(s), 404-1 to 404 n, indicating the availability (or lack ofavailability) of an extension 406 of that MTC-SIB 402. Specifically,each MTC-SIBs includes, in this example, a single bit informationelement (or flag) having, for example, one of two values such as “1” or“0”, respectively indicating whether or not an extension 406 of theMTC-SIB 402 is available.

Furthermore, the extension 406 of that MTC-SIB includes a single bitinformation element (or flag) having, for example, one of two valuessuch as “1” or “0”, respectively indicating whether or not a furtherextension 410 of that MTC-SIB is available. Thus, in the example shownin FIG. 6, MTC-SIB 402-1 includes a bit 404-1 having a value of “1”indicating that the extension 406 of the SIB 402-1 is available.Furthermore, the extension 406 of the SIB 402-1 includes a bit 408having a value of “1” indicating that a further extension 410 of the SIB402-1 is available. On the other hand, MTC-SIB 402-n includes a bit404-n having a value of “0” indicating that no extension of the SIB402-n is available. Thus, the bit effectively functions as a pointerindicating availability of an extension (or further extension).

In practice, this example may be implemented for the Rel-13 version ofthe standards relating to MTC devices by setting the bit to “0” andallowing future releases to allow the bit to be set to “1” and definethe extension part. For example, the extension part could define: themessage for the extension part of MTC-SIB #n (TBS) and its schedulingscheme, a resource allocation (RA) (including time and spectrum positionand repetition times), or transmission formats (MCS, RV, etc.).

Alternatively, as illustrated in FIG. 7, any one of a plurality ofMTC-SIBs 502 can include a bit 504 indicating the general availabilityof an extension 506 of system information for any of that plurality ofMTC-SIBs 502. That is, any one of a plurality of MTC-SIBs 502 caninclude a bit 504 (or flag) having, for example, one of two values suchas “1” or “0”, respectively indicating whether or not an extension 506of system information as a whole is or is not available. Furthermore,the extended system information 506 itself can include a bit 508 having,for example, one of two values such as “1” or “0”, respectivelyindicating whether or not a further extension of the system informationis generally available. For example, as shown in FIG. 5, the MTC-SIB502-1 includes a bit 504 having a value of “1” to indicate that there isan extension 506 to the system information. The extension 506 itselfincludes a bit 508 having a value of “1” to indicate that there is afurther extension 510 of the system information.

In practice, this example may be implemented for the Rel-13 version ofthe standards relating to MTC devices by setting the bit to “0” andallowing future releases to allow the bit to be set to “1” and definethe contents of the extension part(s). For example, the extensionpart(s) could define: the message(s) for the extension information namedas MTCSIB—extension (TBS) and their scheduling scheme, resourceallocation (RA) (including time and spectrum position and repetitiontimes), or transmission formats (MCS, RV, etc.).

Optionally, the corresponding scheduling information of the extensionpart can be indicated.

EXAMPLE 3 Operation—Third Example

A third exemplary way in which an MTC common control transmission can beprovided in the system shown in FIG. 1 is illustrated in FIGS. 8 and 9in which bit(s) in one MTC-SIB can be used to indicate availability of asubsequent MTC-SIB.

As seen in FIG. 8, MTC-SIB_(n) 602-n can include one or more bits toindicate the availability of MTC-SIB_(n+1) 602-n+1. It will beappreciated that the MTC-SIBs may also, optionally, include thecorresponding scheduling information for the next MTC-SIB.

Referring to FIG. 9 which illustrates how a UE 3 can read and interpretthe MTC-SIBs, at step S902 the UE first reads MTC-SIB₁ 601-1, which usesthe PBCH like way with fixed message size and scheduling scheme. Afterdecoding MTC-SIB₁ 601-1, the UE 3 knows that there is another MTC-SIB601-2, denoted as MTC-SIB₂. Thus, at step S904, the UE 3 reads MTC-SIB₂601-2 and, after decoding it, the UE 3 determines, from the presence ofbit 604-2 with a value of “1” that there is yet another MTC-SIB, denotedas MTC-SIB₃ 601-3. Accordingly, at step S906, the UE 3 reads MTC-SIB₃601-3 to determine that there is no further MTC-SIB, i.e., the bit 604-3has a value of “0”.

The MTC-SIB_(n) and its scheduled MTC-SIB_(n+1) can be in the samerelease or in neighbour releases.

FIGS. 10a and 10b show how and where bit(s) can be added to indicate theextension of MTC-SIB or the subsequent MTC-SIB, in accordance with thesecond and third examples. For example, as shown in FIG. 10 a, it ispossible to include an IE in MTC-SIB message. Alternatively, as shown inFIG. 10 b, it is possible to add the information at the end of the TB inthe physical layer.

EXAMPLE 4 Operation—Fourth Example

A fourth exemplary way in which an MTC common control transmission canbe provided in the system shown in FIG. 1 is illustrated in FIG. 11a inwhich one MTC-SIB includes information indicating availability of allother MTC-SIBs and FIG. 11b in which scheduling information is alsoincluded for all other MTC-SIBs.

Specifically, FIGS. 11a and 11b provide two examples of how suchinformation can be included in an MTC-SIB. As seen in FIG. 11 a, theinformation identifying the presence or absence of other MTC-SIBs isprovided as a bitmap. For example, the bitmap could comprise an N-bit(e.g. 20 bit) bitmap corresponding to N (e.g. 20) MTC-SIBs with thefirst bit (‘b0’) indicating the availability of MTC-SIB₁ the second bit(‘b1’) indicating the availability of MTC-SIB₂ etc. Alternatively, asshown in FIG. 11b the information can be provided as a list in which thefirst entry of the list indicates the availability of the MTC-SIB₁ andoptionally, if it is available, what the corresponding schedulinginformation is, the second entry of the list indicates the availabilityof the MTC-SIB₂ and optionally, if it is available, what thecorresponding scheduling information is.

As seen in FIG. 11 b, the scheduling information for all later MTC-SIBscan be sent in a single advanced MTC-SIB, e.g. MTC-SIB₁ in otherexamples.

Modifications and Alternatives

Detailed exemplary embodiments have been described above. As thoseskilled in the art will appreciate, a number of modifications andalternatives can be made to the above exemplary embodiments whilst stillbenefiting from the inventions embodied therein.

It will be appreciated that the inclusion of bits indicating schedulingis entirely optional so that the message size can be kept to a minimum.If not included, scheduling can be predefined. The schedulinginformation can comprise one or more of: periodicity, offset, repeatingtimes/window, resource allocation, and transmission format.

It will be appreciated that these examples described above are notmutually exclusive and any of the examples may be combined within thesame system, either within a single cell and/or in neighbouring cells.

It will be appreciated that although the communication system isdescribed in terms of the base station operating as a E-UTRAN basestation (eNB), the same principles may be applied to base stationsoperating as macro or pico base stations, femto base stations, relaynodes providing elements of base station functionality, home basestations (HeNB), or other such communication nodes.

In the above exemplary embodiments, an LTE telecommunications system wasdescribed. As those skilled in the art will appreciate, the techniquesdescribed in the present application can be employed in othercommunications systems, including earlier 3GPP type systems. Othercommunications nodes or devices may include user devices such as, forexample, personal digital assistants, laptop computers, web browsers,etc.

In the exemplary embodiments described above, the base station and thecommunication device each include transceiver circuitry. Typically, thiscircuitry will be formed by dedicated hardware circuits. However, insome exemplary embodiments, part of the transceiver circuitry may beimplemented as software run by the corresponding controller.

In the above exemplary embodiments, a number of software modules weredescribed. As those skilled in the art will appreciate, the softwaremodules may be provided in compiled or un-compiled form and may besupplied to the base station or the user device as a signal over acomputer network, or on a recording medium. Further, the functionalityperformed by part or all of this software may be performed using one ormore dedicated hardware circuits.

In the above exemplary embodiments, machine-type communication devicesand mobile telephones are described. However, it will be appreciatedthat mobile telephones (and similar user equipment) may also beconfigured to operate as machine-type communication devices. Forexample, the mobile telephone 3-1 may include (and/or provide thefunctionality of) the MTC module 45.

Examples of MTC Applications

It will be appreciated that each communication device may support one ormore MTC applications. Some examples of MTC applications are listed inthe following table (source: 3GPP TS 22.368, Annex B). This list is notexhaustive and is intended to be indicative of the scope of machine-typecommunication applications.

TABLE 1 Service Area MTC applications Security Surveillance systemsBackup for landline Control of physical access (e.g. to buildings)Car/driver security Tracking & Tracing Fleet Management Order ManagementPay as you drive Asset Tracking Navigation Traffic information Roadtolling Road traffic optimisation/steering Payment Point of salesVending machines Gaming machines Health Monitoring vital signsSupporting the aged or handicapped Web Access Telemedicine points Remotediagnostics Remote Sensors Maintenance/Control Lighting Pumps ValvesElevator control Vending machine control Vehicle diapostics MeteringPower Gas Water Heating Grid control Industrial metering ConsumerDevices Digital photo frame Digital camera eBook

It will be appreciated that although the enhanced control-less commoncontrol transmission scheme is disclosed with specific reference to MTCdevices where it is particularly advantageous it could also havebenefits for any type of user equipment.

Various other modifications will be apparent to those skilled in the artand will not be described in further detail here.

This application is based upon and claims the benefit of priority fromUK patent application No. 1501618.1, filed on Jan. 30, 2015, thedisclosure of which is incorporated herein in its entirety by reference.

1-30. (canceled)
 31. A first communications apparatus which communicateswith second communications apparatus, the first communications apparatuscomprising; a transceiver configured to receive a Master InformationBlock (MIB) which includes first information; and at least one processorconfigured to determine, based on the first information, a TransportBlock Size (TBS) for System Information Block 1 (SIB1) and a number ofrepetitions of the SIB1, wherein the transceiver is further configuredto receive the SIB1 based on the first information.
 32. A firstcommunications apparatus according to claim 31, wherein the MIB furtherincludes Modulation and Coding Scheme (MCS) information.
 33. A firstcommunications apparatus according to claim 31, wherein the SIB1includes information indicating repetition times for a number ofrepetitions of other system information.
 34. A first communicationsapparatus according to claim 31, wherein the first information comprisesan indication of one of a plurality of predefined configurations of TBSand number of repetitions, wherein the TBS and the number of repetitionsfor SIB1 is determined based on the indication.
 35. A firstcommunications apparatus according to claim 33, wherein the other systeminformation comprises system information for Machine Type Communications(MTC) apparatus.
 36. A first communications apparatus according to claim31, wherein the first communications apparatus is a mobile station andthe second communications apparatus is a base station.
 37. A firstcommunications apparatus according to claim 31, wherein the SIB1 istransmitted by a Physical Downlink Shared Channel (PDSCH).
 38. A firstcommunications apparatus according to claim 31, wherein the MIB istransmitted by a Physical Broadcast Channel (PBCH).
 39. A firstcommunications apparatus according to claim 31, wherein the SIB1indicates TBS information for other system information.
 40. A methodperformed by a first communications apparatus which communicates withsecond communications apparatus, the method comprising; receiving aMaster Information Block (MIB) which includes first information;determining, based on the first information, a Transport Block Size(TBS) for System Information Block 1 (SIB1) and a number of repetitionsof the SIB1; and receiving the SIB1 based on the first information. 41.A method according to claim 40, wherein the MIB further includesModulation and Coding Scheme (MCS) information.
 42. A method accordingto claim 40, wherein the SIB1 includes information indicating repetitiontimes for a number of repetitions of other system information.
 43. Amethod according to claim 40, wherein the first information comprises anindication of one of a plurality of predefined configurations of TBS andnumber of repetitions, wherein the TBS and the number of repetitions forSIB1 is determined based on the indication.
 44. A method according toclaim 42, wherein the other system information comprises systeminformation for Machine Type Communications (MTC) apparatus.
 45. Amethod according to claim 40, wherein the first communications apparatusis a mobile station and the second communications apparatus is a basestation.
 46. A method according to claim 40, wherein the SIB1 istransmitted by a Physical Downlink Shared Channel (PDSCH).
 47. A methodaccording to claim 40, wherein the MIB is transmitted by a PhysicalBroadcast Channel (PBCH).
 48. A method according to claim 40, whereinthe SIB1 indicates TBS information for other system information.
 49. Asecond communications apparatus which communicates with firstcommunications apparatus, the second communications apparatuscomprising; a transceiver configured to: transmit a Master InformationBlock (MIB) which includes first information representing a TransportBlock Size (TBS) for System Information Block 1 (SIB1) and a number ofrepetitions of the SIB1; and transmit the SIB1 based on the TBS andnumber of repetitions.
 50. A method performed by a second communicationsapparatus which communicates with first communications apparatus, themethod comprising; transmitting a Master Information Block (MIB) whichincludes first information representing a Transport Block Size (TBS) forSystem Information Block 1 (SIB1) and a number of repetitions of theSIB1; and transmitting the SIB1 based on the TBS and number ofrepetitions.
 51. A non-transitory computer implementable instructionsproduct comprising computer implementable instructions for causing aprogrammable communications device to perform the method of claim 40.